The present invention relates to an apparatus for developing latent images which are exposed onto electroradiographic sheet-like carriers. More particularly, the invention relates to an electrophotographic developing apparatus which can be resorted to for conversion of latent images into permanent images. Still more particularly, the invention relates to improvements in electrophotographic developing techniques which involve the placing of carriers of latent images into a body of dielectric liquid which is disposed between two spaced-apart electrodes and contains a dispersion of charged toner particles. The carrier of latent images in the body of dielectric liquid is adjacent to one of the electrodes.
Developing techniques of the just outlined character are often employed in the electroradiographic field because the development of latent images is highly satisfactory. This is due to the fact that the intensity of development is proportional to or improves with the extent of changes in the charge of different portions of the latent electrostatic image of an object, e.g., an object which has been examined with X-rays. Moreover, the just discussed mode of development renders it possible to completely eliminate the so-called edge effect. This is the effect according to which, in many types of developing techniques, only the marginal portions or edges of relatively large dark fields of a latent image are reproduced in full black color. The color varies from the edges toward the center, namely, from fully black to grey and even to white. Avoidance of the just discussed edge effect is especially desirable and advantageous in connection with electrophotographic reproduction of written, typed and/or printed documents.
On the other hand, the presence of some edge effect in reproductions of images which are formed by resorting to an electroradiographic technique is often advantageous because the edge effect enhances the detectability of certain details of the developed image, for example, details which are likely to be of interest to a physician.